<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html401/loose.dtd"> <html> <!-- Created on December, 2 2016 by texi2html 1.78a --> <!-- Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author) Karl Berry <karl@freefriends.org> Olaf Bachmann <obachman@mathematik.uni-kl.de> and many others. Maintained by: Many creative people. Send bugs and suggestions to <texi2html-bug@nongnu.org> --> <head> <title>GNU libunistring: 13. Normalization forms (composition and decomposition) <uninorm.h></title> <meta name="description" content="GNU libunistring: 13. Normalization forms (composition and decomposition) <uninorm.h>"> <meta name="keywords" content="GNU libunistring: 13. Normalization forms (composition and decomposition) <uninorm.h>"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="texi2html 1.78a"> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <style type="text/css"> <!-- a.summary-letter {text-decoration: none} pre.display {font-family: serif} pre.format {font-family: serif} pre.menu-comment {font-family: serif} pre.menu-preformatted {font-family: serif} pre.smalldisplay {font-family: serif; font-size: smaller} pre.smallexample {font-size: smaller} pre.smallformat {font-family: serif; font-size: smaller} pre.smalllisp {font-size: smaller} span.roman {font-family:serif; font-weight:normal;} span.sansserif {font-family:sans-serif; font-weight:normal;} ul.toc {list-style: none} --> </style> </head> <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> <table cellpadding="1" cellspacing="1" border="0"> <tr><td valign="middle" align="left">[<a href="libunistring_12.html#SEC47" title="Beginning of this chapter or previous chapter"> << </a>]</td> <td valign="middle" align="left">[<a href="libunistring_14.html#SEC54" title="Next chapter"> >> </a>]</td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left">[<a href="libunistring.html#SEC_Top" title="Cover (top) of document">Top</a>]</td> <td valign="middle" align="left">[<a href="libunistring.html#SEC_Contents" title="Table of contents">Contents</a>]</td> <td valign="middle" align="left">[<a href="libunistring_19.html#SEC77" title="Index">Index</a>]</td> <td valign="middle" align="left">[<a href="libunistring_abt.html#SEC_About" title="About (help)"> ? </a>]</td> </tr></table> <hr size="2"> <a name="uninorm_002eh"></a> <a name="SEC48"></a> <h1 class="chapter"> <a href="libunistring.html#TOC48">13. Normalization forms (composition and decomposition) <code><uninorm.h></code></a> </h1> <p>This include file defines functions for transforming Unicode strings to one of the four normal forms, known as NFC, NFD, NKFC, NFKD. These transformations involve decomposition and — for NFC and NFKC — composition of Unicode characters. </p> <hr size="6"> <a name="Decomposition-of-characters"></a> <a name="SEC49"></a> <h2 class="section"> <a href="libunistring.html#TOC49">13.1 Decomposition of Unicode characters</a> </h2> <p>The following enumerated values are the possible types of decomposition of a Unicode character. </p> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_CANONICAL</b> <a name="IDX767"></a> </dt> <dd><p>Denotes canonical decomposition. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_FONT</b> <a name="IDX768"></a> </dt> <dd><p>UCD marker: <code><font></code>. Denotes a font variant (e.g. a blackletter form). </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_NOBREAK</b> <a name="IDX769"></a> </dt> <dd><p>UCD marker: <code><noBreak></code>. Denotes a no-break version of a space or hyphen. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_INITIAL</b> <a name="IDX770"></a> </dt> <dd><p>UCD marker: <code><initial></code>. Denotes an initial presentation form (Arabic). </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_MEDIAL</b> <a name="IDX771"></a> </dt> <dd><p>UCD marker: <code><medial></code>. Denotes a medial presentation form (Arabic). </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_FINAL</b> <a name="IDX772"></a> </dt> <dd><p>UCD marker: <code><final></code>. Denotes a final presentation form (Arabic). </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_ISOLATED</b> <a name="IDX773"></a> </dt> <dd><p>UCD marker: <code><isolated></code>. Denotes an isolated presentation form (Arabic). </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_CIRCLE</b> <a name="IDX774"></a> </dt> <dd><p>UCD marker: <code><circle></code>. Denotes an encircled form. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_SUPER</b> <a name="IDX775"></a> </dt> <dd><p>UCD marker: <code><super></code>. Denotes a superscript form. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_SUB</b> <a name="IDX776"></a> </dt> <dd><p>UCD marker: <code><sub></code>. Denotes a subscript form. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_VERTICAL</b> <a name="IDX777"></a> </dt> <dd><p>UCD marker: <code><vertical></code>. Denotes a vertical layout presentation form. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_WIDE</b> <a name="IDX778"></a> </dt> <dd><p>UCD marker: <code><wide></code>. Denotes a wide (or zenkaku) compatibility character. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_NARROW</b> <a name="IDX779"></a> </dt> <dd><p>UCD marker: <code><narrow></code>. Denotes a narrow (or hankaku) compatibility character. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_SMALL</b> <a name="IDX780"></a> </dt> <dd><p>UCD marker: <code><small></code>. Denotes a small variant form (CNS compatibility). </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_SQUARE</b> <a name="IDX781"></a> </dt> <dd><p>UCD marker: <code><square></code>. Denotes a CJK squared font variant. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_FRACTION</b> <a name="IDX782"></a> </dt> <dd><p>UCD marker: <code><fraction></code>. Denotes a vulgar fraction form. </p></dd></dl> <dl> <dt><u>Constant:</u> int <b>UC_DECOMP_COMPAT</b> <a name="IDX783"></a> </dt> <dd><p>UCD marker: <code><compat></code>. Denotes an otherwise unspecified compatibility character. </p></dd></dl> <p>The following constant denotes the maximum size of decomposition of a single Unicode character. </p> <dl> <dt><u>Macro:</u> unsigned int <b>UC_DECOMPOSITION_MAX_LENGTH</b> <a name="IDX784"></a> </dt> <dd><p>This macro expands to a constant that is the required size of buffer passed to the <code>uc_decomposition</code> and <code>uc_canonical_decomposition</code> functions. </p></dd></dl> <p>The following functions decompose a Unicode character. </p> <dl> <dt><u>Function:</u> int <b>uc_decomposition</b><i> (ucs4_t <var>uc</var>, int *<var>decomp_tag</var>, ucs4_t *<var>decomposition</var>)</i> <a name="IDX785"></a> </dt> <dd><p>Returns the character decomposition mapping of the Unicode character <var>uc</var>. <var>decomposition</var> must point to an array of at least <code>UC_DECOMPOSITION_MAX_LENGTH</code> <code>ucs_t</code> elements. </p> <p>When a decomposition exists, <code><var>decomposition</var>[0..<var>n</var>-1]</code> and <code>*<var>decomp_tag</var></code> are filled and <var>n</var> is returned. Otherwise -1 is returned. </p></dd></dl> <dl> <dt><u>Function:</u> int <b>uc_canonical_decomposition</b><i> (ucs4_t <var>uc</var>, ucs4_t *<var>decomposition</var>)</i> <a name="IDX786"></a> </dt> <dd><p>Returns the canonical character decomposition mapping of the Unicode character <var>uc</var>. <var>decomposition</var> must point to an array of at least <code>UC_DECOMPOSITION_MAX_LENGTH</code> <code>ucs_t</code> elements. </p> <p>When a decomposition exists, <code><var>decomposition</var>[0..<var>n</var>-1]</code> is filled and <var>n</var> is returned. Otherwise -1 is returned. </p></dd></dl> <hr size="6"> <a name="Composition-of-characters"></a> <a name="SEC50"></a> <h2 class="section"> <a href="libunistring.html#TOC50">13.2 Composition of Unicode characters</a> </h2> <p>The following function composes a Unicode character from two Unicode characters. </p> <dl> <dt><u>Function:</u> ucs4_t <b>uc_composition</b><i> (ucs4_t <var>uc1</var>, ucs4_t <var>uc2</var>)</i> <a name="IDX787"></a> </dt> <dd><p>Attempts to combine the Unicode characters <var>uc1</var>, <var>uc2</var>. <var>uc1</var> is known to have canonical combining class 0. </p> <p>Returns the combination of <var>uc1</var> and <var>uc2</var>, if it exists. Returns 0 otherwise. </p> <p>Not all decompositions can be recombined using this function. See the Unicode file ‘<tt>CompositionExclusions.txt</tt>’ for details. </p></dd></dl> <hr size="6"> <a name="Normalization-of-strings"></a> <a name="SEC51"></a> <h2 class="section"> <a href="libunistring.html#TOC51">13.3 Normalization of strings</a> </h2> <p>The Unicode standard defines four normalization forms for Unicode strings. The following type is used to denote a normalization form. </p> <dl> <dt><u>Type:</u> <b>uninorm_t</b> <a name="IDX788"></a> </dt> <dd><p>An object of type <code>uninorm_t</code> denotes a Unicode normalization form. This is a scalar type; its values can be compared with <code>==</code>. </p></dd></dl> <p>The following constants denote the four normalization forms. </p> <dl> <dt><u>Macro:</u> uninorm_t <b>UNINORM_NFD</b> <a name="IDX789"></a> </dt> <dd><p>Denotes Normalization form D: canonical decomposition. </p></dd></dl> <dl> <dt><u>Macro:</u> uninorm_t <b>UNINORM_NFC</b> <a name="IDX790"></a> </dt> <dd><p>Normalization form C: canonical decomposition, then canonical composition. </p></dd></dl> <dl> <dt><u>Macro:</u> uninorm_t <b>UNINORM_NFKD</b> <a name="IDX791"></a> </dt> <dd><p>Normalization form KD: compatibility decomposition. </p></dd></dl> <dl> <dt><u>Macro:</u> uninorm_t <b>UNINORM_NFKC</b> <a name="IDX792"></a> </dt> <dd><p>Normalization form KC: compatibility decomposition, then canonical composition. </p></dd></dl> <p>The following functions operate on <code>uninorm_t</code> objects. </p> <dl> <dt><u>Function:</u> bool <b>uninorm_is_compat_decomposing</b><i> (uninorm_t <var>nf</var>)</i> <a name="IDX793"></a> </dt> <dd><p>Tests whether the normalization form <var>nf</var> does compatibility decomposition. </p></dd></dl> <dl> <dt><u>Function:</u> bool <b>uninorm_is_composing</b><i> (uninorm_t <var>nf</var>)</i> <a name="IDX794"></a> </dt> <dd><p>Tests whether the normalization form <var>nf</var> includes canonical composition. </p></dd></dl> <dl> <dt><u>Function:</u> uninorm_t <b>uninorm_decomposing_form</b><i> (uninorm_t <var>nf</var>)</i> <a name="IDX795"></a> </dt> <dd><p>Returns the decomposing variant of the normalization form <var>nf</var>. This maps NFC,NFD → NFD and NFKC,NFKD → NFKD. </p></dd></dl> <p>The following functions apply a Unicode normalization form to a Unicode string. </p> <dl> <dt><u>Function:</u> uint8_t * <b>u8_normalize</b><i> (uninorm_t <var>nf</var>, const uint8_t *<var>s</var>, size_t <var>n</var>, uint8_t *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i> <a name="IDX796"></a> </dt> <dt><u>Function:</u> uint16_t * <b>u16_normalize</b><i> (uninorm_t <var>nf</var>, const uint16_t *<var>s</var>, size_t <var>n</var>, uint16_t *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i> <a name="IDX797"></a> </dt> <dt><u>Function:</u> uint32_t * <b>u32_normalize</b><i> (uninorm_t <var>nf</var>, const uint32_t *<var>s</var>, size_t <var>n</var>, uint32_t *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i> <a name="IDX798"></a> </dt> <dd><p>Returns the specified normalization form of a string. </p></dd></dl> <hr size="6"> <a name="Normalizing-comparisons"></a> <a name="SEC52"></a> <h2 class="section"> <a href="libunistring.html#TOC52">13.4 Normalizing comparisons</a> </h2> <p>The following functions compare Unicode string, ignoring differences in normalization. </p> <dl> <dt><u>Function:</u> int <b>u8_normcmp</b><i> (const uint8_t *<var>s1</var>, size_t <var>n1</var>, const uint8_t *<var>s2</var>, size_t <var>n2</var>, uninorm_t <var>nf</var>, int *<var>resultp</var>)</i> <a name="IDX799"></a> </dt> <dt><u>Function:</u> int <b>u16_normcmp</b><i> (const uint16_t *<var>s1</var>, size_t <var>n1</var>, const uint16_t *<var>s2</var>, size_t <var>n2</var>, uninorm_t <var>nf</var>, int *<var>resultp</var>)</i> <a name="IDX800"></a> </dt> <dt><u>Function:</u> int <b>u32_normcmp</b><i> (const uint32_t *<var>s1</var>, size_t <var>n1</var>, const uint32_t *<var>s2</var>, size_t <var>n2</var>, uninorm_t <var>nf</var>, int *<var>resultp</var>)</i> <a name="IDX801"></a> </dt> <dd><p>Compares <var>s1</var> and <var>s2</var>, ignoring differences in normalization. </p> <p><var>nf</var> must be either <code>UNINORM_NFD</code> or <code>UNINORM_NFKD</code>. </p> <p>If successful, sets <code>*<var>resultp</var></code> to -1 if <var>s1</var> < <var>s2</var>, 0 if <var>s1</var> = <var>s2</var>, 1 if <var>s1</var> > <var>s2</var>, and returns 0. Upon failure, returns -1 with <code>errno</code> set. </p></dd></dl> <a name="IDX802"></a> <a name="IDX803"></a> <dl> <dt><u>Function:</u> char * <b>u8_normxfrm</b><i> (const uint8_t *<var>s</var>, size_t <var>n</var>, uninorm_t <var>nf</var>, char *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i> <a name="IDX804"></a> </dt> <dt><u>Function:</u> char * <b>u16_normxfrm</b><i> (const uint16_t *<var>s</var>, size_t <var>n</var>, uninorm_t <var>nf</var>, char *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i> <a name="IDX805"></a> </dt> <dt><u>Function:</u> char * <b>u32_normxfrm</b><i> (const uint32_t *<var>s</var>, size_t <var>n</var>, uninorm_t <var>nf</var>, char *<var>resultbuf</var>, size_t *<var>lengthp</var>)</i> <a name="IDX806"></a> </dt> <dd><p>Converts the string <var>s</var> of length <var>n</var> to a NUL-terminated byte sequence, in such a way that comparing <code>u8_normxfrm (<var>s1</var>)</code> and <code>u8_normxfrm (<var>s2</var>)</code> with the <code>u8_cmp2</code> function is equivalent to comparing <var>s1</var> and <var>s2</var> with the <code>u8_normcoll</code> function. </p> <p><var>nf</var> must be either <code>UNINORM_NFC</code> or <code>UNINORM_NFKC</code>. </p></dd></dl> <dl> <dt><u>Function:</u> int <b>u8_normcoll</b><i> (const uint8_t *<var>s1</var>, size_t <var>n1</var>, const uint8_t *<var>s2</var>, size_t <var>n2</var>, uninorm_t <var>nf</var>, int *<var>resultp</var>)</i> <a name="IDX807"></a> </dt> <dt><u>Function:</u> int <b>u16_normcoll</b><i> (const uint16_t *<var>s1</var>, size_t <var>n1</var>, const uint16_t *<var>s2</var>, size_t <var>n2</var>, uninorm_t <var>nf</var>, int *<var>resultp</var>)</i> <a name="IDX808"></a> </dt> <dt><u>Function:</u> int <b>u32_normcoll</b><i> (const uint32_t *<var>s1</var>, size_t <var>n1</var>, const uint32_t *<var>s2</var>, size_t <var>n2</var>, uninorm_t <var>nf</var>, int *<var>resultp</var>)</i> <a name="IDX809"></a> </dt> <dd><p>Compares <var>s1</var> and <var>s2</var>, ignoring differences in normalization, using the collation rules of the current locale. </p> <p><var>nf</var> must be either <code>UNINORM_NFC</code> or <code>UNINORM_NFKC</code>. </p> <p>If successful, sets <code>*<var>resultp</var></code> to -1 if <var>s1</var> < <var>s2</var>, 0 if <var>s1</var> = <var>s2</var>, 1 if <var>s1</var> > <var>s2</var>, and returns 0. Upon failure, returns -1 with <code>errno</code> set. </p></dd></dl> <hr size="6"> <a name="Normalization-of-streams"></a> <a name="SEC53"></a> <h2 class="section"> <a href="libunistring.html#TOC53">13.5 Normalization of streams of Unicode characters</a> </h2> <p>A “stream of Unicode characters” is essentially a function that accepts an <code>ucs4_t</code> argument repeatedly, optionally combined with a function that “flushes” the stream. </p> <dl> <dt><u>Type:</u> <b>struct uninorm_filter</b> <a name="IDX810"></a> </dt> <dd><p>This is the data type of a stream of Unicode characters that normalizes its input according to a given normalization form and passes the normalized character sequence to the encapsulated stream of Unicode characters. </p></dd></dl> <dl> <dt><u>Function:</u> struct uninorm_filter * <b>uninorm_filter_create</b><i> (uninorm_t <var>nf</var>, int (*<var>stream_func</var>) (void *<var>stream_data</var>, ucs4_t <var>uc</var>), void *<var>stream_data</var>)</i> <a name="IDX811"></a> </dt> <dd><p>Creates and returns a normalization filter for Unicode characters. </p> <p>The pair (<var>stream_func</var>, <var>stream_data</var>) is the encapsulated stream. <code><var>stream_func</var> (<var>stream_data</var>, <var>uc</var>)</code> receives the Unicode character <var>uc</var> and returns 0 if successful, or -1 with <code>errno</code> set upon failure. </p> <p>Returns the new filter, or NULL with <code>errno</code> set upon failure. </p></dd></dl> <dl> <dt><u>Function:</u> int <b>uninorm_filter_write</b><i> (struct uninorm_filter *<var>filter</var>, ucs4_t <var>uc</var>)</i> <a name="IDX812"></a> </dt> <dd><p>Stuffs a Unicode character into a normalizing filter. Returns 0 if successful, or -1 with <code>errno</code> set upon failure. </p></dd></dl> <dl> <dt><u>Function:</u> int <b>uninorm_filter_flush</b><i> (struct uninorm_filter *<var>filter</var>)</i> <a name="IDX813"></a> </dt> <dd><p>Brings data buffered in the filter to its destination, the encapsulated stream. </p> <p>Returns 0 if successful, or -1 with <code>errno</code> set upon failure. </p> <p>Note! If after calling this function, additional characters are written into the filter, the resulting character sequence in the encapsulated stream will not necessarily be normalized. </p></dd></dl> <dl> <dt><u>Function:</u> int <b>uninorm_filter_free</b><i> (struct uninorm_filter *<var>filter</var>)</i> <a name="IDX814"></a> </dt> <dd><p>Brings data buffered in the filter to its destination, the encapsulated stream, then closes and frees the filter. </p> <p>Returns 0 if successful, or -1 with <code>errno</code> set upon failure. </p></dd></dl> <hr size="6"> <table cellpadding="1" cellspacing="1" border="0"> <tr><td valign="middle" align="left">[<a href="#SEC48" title="Beginning of this chapter or previous chapter"> << </a>]</td> <td valign="middle" align="left">[<a href="libunistring_14.html#SEC54" title="Next chapter"> >> </a>]</td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left"> </td> <td valign="middle" align="left">[<a href="libunistring.html#SEC_Top" title="Cover (top) of document">Top</a>]</td> <td valign="middle" align="left">[<a href="libunistring.html#SEC_Contents" title="Table of contents">Contents</a>]</td> <td valign="middle" align="left">[<a href="libunistring_19.html#SEC77" title="Index">Index</a>]</td> <td valign="middle" align="left">[<a href="libunistring_abt.html#SEC_About" title="About (help)"> ? </a>]</td> </tr></table> <p> <font size="-1"> This document was generated by <em>Daiki Ueno</em> on <em>December, 2 2016</em> using <a href="http://www.nongnu.org/texi2html/"><em>texi2html 1.78a</em></a>. </font> <br> </p> </body> </html>